In a valve device such as a pressure reducing valve applied to an oil hydraulic circuit, an oil filter is interposed in an oil passage for supplying oil to a spool. As the oil filter, an oil filter in which a wire gauge is used is present. However, recently, an oil filter in which passage holes are formed in a metal thin plate is also provided. With the oil filter of this type, it is unlikely that fluctuation in the passage holes due to loosening of the wire gauge is caused. It is possible to easily secure a certain level of quality (see, for example, Patent Literature 1).